Heat oven to 350 degrees.,Grease and flour 15 1/2 X 10 1/2 X 1 inch jelly roll pan.,Combine water, butter, and cocoa in medium saucepan.,Cook over medium heat, stirring occasionally until mixture boils.,Boil for one minute.,Remove from heat. Stir together sugar, flour, baking soda, and salt in a large bowl.,Add eggs and sour cream.,______,Add cocoa mixture. Beat until blended.,Pour into prepared pan.,Bake 25 to 30 minutes or until wooden toothpick inserted comes out clean.,Cool on wire rack.,Prepare peanut butter chip frosting and spread over cake.,Prepare chocolate garnish and drizzle over top.